Type Safe Assets Handling in Swift
2 likes2,940 views
Type Safe Assets Handling in Swift
Type Safe Assets Handling in Swift
- 1. Type Safe Resource Handling in Swift 2015/10/13 potatotips #22
- 3. 本日の内容 ? リソースを静的型付けし、Type Safeに扱う方法 をお話しします。 ? リソースとは? Asset Catalog ?UIStoryboard ? Localizable.strings
- 4. ? リソースのインスタンス生成時? String型の値で指定 Objective-C style // Assets Catalog let img = UIImage(named: "Sample") // Storyboard let sb = UIStoryboard(name: "Sample", bundle: nil) .instantiateViewControllerWithIdentifier("Sample") as? SampleViewController // Localizable.strings let str = NSLocalizedString("Sample", comment: “")
- 5. 問題点 ? コンパイラによるチェックが不可 ? → 指定方法がStringのため? ? 実行時にリソースの存在チェック ? → ランタイムエラーが発生するリスクあり ? 戻り値の型 : Optional<T> ? → 使用時にunwrapする必要がある // 存在しない場合 let sb = UIStoryboard(name: UIApplicationDidBecomeActiveNotification, bundle: nil) // Terminating app due to uncaught exception 'NSInvalidArgumentException', // reason: 'Could not find a storyboard named 'Sample' in bundle NSBundle let img: UIImage? = UIImage(named: NSURLErrorDomain) let vc: SampleViewController? = sb.instantiateViewControllerWithIdentifier("Sample") as? SampleViewController
- 6. 改善ポイント Swift は Type Safe な言語！ ? リソースのStringに型情報を持たせる
- 7. App Speci?c Enum extension UIImage { enum Asset: String { case Camera = "Camera" case Home = "Home" case Mail = "Mail" } convenience init!(asset: Asset) { self.init(named: asset.rawValue) } } Asset ID / Enumの対応付け ? Initializer: Enumでリソースを指定 ? Non Optional な戻り値 （リソースの存在が担保されている）
- 8. Usage let camera = UIImage(asset: .Camera) let home = UIImage(asset: .Home) let mail = UIImage(asset: .Mail)
- 9. Pros / Cons ? Pros 引数を型付けできる → コンパイル時チェックが可能 → Non-optionalな型が戻り値となる ? Cons リソースを更新する度にEnum値を更新する必要がある?
- 10. ? CLツール : リソース用Swiftコードを自動生成 Asset Catalog (UIImage) UIStoryboard Localizable.strings UIColor ? Homebrewに対応? https://github.com/AliSoftware/SwiftGen SwiftGen ?$ ?brew ?install ?swiftgen ?
- 11. Usage: UIStoryboard ? コマンドラインを実行 swiftgen-?‐storyboard ?/dir/to/storyboards ?> ?Storyboards.swift
- 12. // Storyboards.swift protocol StoryboardScene : RawRepresentable { static var storyboardName : String { get } static func storyboard() -> UIStoryboard static func initialViewController() -> UIViewController func viewController() -> UIViewController static func viewController(identifier: Self) -> UIViewController } extension StoryboardScene where Self.RawValue == String { static func storyboard() -> UIStoryboard { return UIStoryboard(name: self.storyboardName, bundle: nil) } static func initialViewController() -> UIViewController { return storyboard().instantiateInitialViewController()! } func viewController() -> UIViewController { return Self.storyboard().instantiateViewControllerWithIdentifier(self.rawValue) } static func viewController(identifier: Self) -> UIViewController { return identifier.viewController() } } via https://github.com/AliSoftware/SwiftGen
- 13. // Storyboards.swift extension UIStoryboard { struct Scene { enum Wizard : String, StoryboardScene { static let storyboardName = "Wizard" case CreateAccount = "CreateAccount" static func createAccountViewController() -> CreateAccViewController { return Wizard.CreateAccount.viewController() as! CreateAccViewController } case ValidatePassword = "Validate_Password" static func validatePasswordViewController() -> UIViewController { return Wizard.ValidatePassword.viewController() } } enum Message : String, StoryboardScene { static let storyboardName = "Message" case Composer = "Composer" static func composerViewController() -> UIViewController { return Message.Composer.viewController() } case URLChooser = "URLChooser" static func urlChooserViewController() -> XXPickerViewController { return Message.URLChooser.viewController() as! XXPickerViewController } } } struct Segue { enum Message : String { case Custom = "Custom" case Back = "Back" case NonCustom = "NonCustom" } } } Storyboard IDに対応 Storyboardファイルに対応 via https://github.com/AliSoftware/SwiftGen
- 14. Usage // Initial VC let initialVC = UIStoryboard.Scene.Wizard.initialViewController() // Generic ViewController constructor, returns a UIViewController instance let validateVC = UIStoryboard.Scene.Wizard.ValidatePassword.viewController() // Dedicated type var that returns the right type of VC (CreateAccViewController here) let createVC = UIStoryboard.Scene.Wizard.createAccountViewController() override func prepareForSegue(_ segue: UIStoryboardSegue, sender sender: AnyObject?) { switch UIStoryboard.Segue.Message(rawValue: segue.identifier)! { case .Custom: // Prepare for your custom segue transition case .Back: // Prepare for your custom segue transition case .NonCustom: // Prepare for your custom segue transition } } via https://github.com/AliSoftware/SwiftGen
- 15. まとめ ? App Speci?c Enum を利用すると? 静的型付けしてリソースを扱える? ? SwiftGen: リソース用コードを自動生成可能?
- 16. References ? SwiftGen? https://github.com/AliSoftware/SwiftGen? ? ? WWDC’15: Swift in Practice? https://developer.apple.com/videos/wwdc/ 2015/?id=411
- 17. ご静聴ありがとうございました ?